DRV421: DRV421 in +/-15V applications

Nicola Zanforlin

Part Number: DRV421

Hello. DRV421 can be used aven in +/-15V applications (datasheet point 8.2.3).

However an external driver is nesessary because of the limits of the chip. What driver do you suggest? I suppose operational amplifier followed by npn+pnp transistors in a common emitter configuration. In this case what amplifier from TI can be suitable and with what transistors can it work properly?

Thank you

over 2 years ago

0 Javier Contreras4 over 2 years ago

TI__Mastermind 27690 points

Hello Nicola,

I would use something similar to https://www.ti.com/tool/TIPD184. I have attempted that and another option in the lab. This could be a lot of power depending on your configuration so make sure all the required heat sink are done to meet your needs.

I have attached What I attempted in the lab.

DRV421_Measuring_High_Currents_1500A_E2E.pdf

0 Nicola Zanforlin over 2 years ago in reply to Javier Contreras4

Prodigy 30 points

Hi Javier. Nice to hear from you again.

Thank you a lot for the very interesting and useful documentation!

Do you have also some informations about bandwidth and stability of these circuits?

I'll use the circuit in a current feedback loop (laser application) where the current has a triangular shape up to 40KHz, due to the ripple at the chopper switching frequency, and can reach 450A even if only for a short time (tipically 10ms @ 2Hz i.e. 10ms every 500ms) so I'm not worried about power dissipation. The ripple with triangular shape is about 100A pk to pk. My target is to replace commercial sensors that are very expensive and sometimes not so easy to find

+1 Javier Contreras4 over 2 years ago in reply to Nicola Zanforlin

TI__Mastermind 27690 points

Nicola,

Stability should be the same for other DRV421 as the dominate pole should be from your inductor and your Rshunt. Not sure if I shared with you the stability Application Note. https://www.ti.com/lit/pdf/sloa224

As for the bandwidth. The control circuit will dominate at low frequency and the current transformer properties of the core and primary will dominate a higher frequency. You can see that in the System calculator. Make sure you have clamping diodes to give a path for the current when they go beyond the rails.

https://www.ti.com/lit/zip/sloc329 Calculator

https://www.ti.com/lit/an/sloa225/sloa225.pdf Documentation